I know your sick off it.... 2007 Yukon

[05Yukon]

I have a cold air intake, a Corsa Sport cat back, and a BB tune. I can squeeze 15 mpg city and 17 hwy with careful driving. AND I know how to do it!
About the only other thing to do that MIGHT improve mpg is lowering and ditching the 18" Duelers for 20" factory wheels and tires. And I would probably have to drive 2 years to recoup the cost of that!

Switching to 20's will not help your mileage it will make it worse. The larger the wheel the more weight you have on each corner and more weight to turn.

 

[Eagle]

well actually the factory 20s are pretty light, and not real wide. If his 18 duelers are wider or heavier or both, it might help. I can get 20.3 highway on the 20s but i'm 2wd and probably lighter than the nnbs.
I' m get 15 city and 18-19 highway on cruise. I picked up a bit going from 22s to oem 20s & changing all filters, but the change to summer gas helped just as much.

7,8,9. #1 will mostly help you by making more noise and encouraging you to back off the throttle... unless you are a gearhead